The eight days of Sukkot (seven in Israel) are, like those of Passover, of two kinds. The first, second, seventh, and eighth days of the holiday (the first and seventh in Israel) resemble the Sabbath in their festive meals with kiddush, the blessing over wine; their additional prayer service of Musaf; and their restrictions on work, travel, commerce, and other things. In Hebrew, they are known as yamim tovim, literally, “good days,” the singular of which is yom tov. The intermediate four days (five in Israel) lack these elements and are called ḥol ha-mo’ed, “the non-sacred part [ḥol] of the festive [literally, “appointed”] time [ha-mo’ed].”
Whatever Happened to Gut Yontif? Why Jews Started Saying Ḥag Same'aḥ
The history of holiday greetings.